This work is designed to quantitate each of the various types of human serum lipoproteins, measure their apoprotein composition, and to quantitate the very low density and high density lipoprotein subpopulations in: (a) individuals with mammary carcinoma; (b) individuals without cancer but with a family history of cancer; and (c) normal individuals without a family history of cancer. Lipoprotein quantitation will be done by ultracentrifugal and immunochemical methods, apoprotein quantitation by various types of gel electrophoresis, and lipoprotein subpopulation measurements by methods which we have previously developed. The significance of this work is that lipoprotein aberrations are known to occur in certain types of cancer. To understand the processes which give rise to the aberrations, we must first ascertain their chemistry.